8.S.V.4

Energy in animals: respiration Animal chemical reactions do the opposite of plants—they use up oxygen and release CO2. In animals the chief process is not photosynthesis but respiration, that is, the creation of new compounds through oxidation. Animals cannot make carbohydrates, proteins, and fats from elements. They must eat these organic compounds from plants or other animals, and create them through respiration. Respiration uses oxygen and releases CO2, creating an interdependence and balance between plant and animal life.